Turbo-compressor train with rolling bearings and related assembly method

ABSTRACT

A turbo-compressor train and a method for assembling a turbo-compressor train. The train includes a gas turbine engine configured to transform thermal energy into mechanical energy; a centrifugal compressor having a shaft connected to a shaft of the gas turbine engine; and a single lube pump configured to provide synthetic oil to the gas turbine engine and the centrifugal compressor. The gas turbine engine, the centrifugal compressor and the single lube pump each has only rolling bearings.

BACKGROUND OF THE INVENTION

Embodiments of the subject matter disclosed herein generally relate tomethods and systems and, more particularly, to mechanisms and techniquesfor providing an entire turbo-compressor train with a single lube pumpand/or with a single lubrication oil medium.

Gas turbines are used in many sectors of the industry, from military topower generation. They are used mainly to produce electrical energy.However, some gas turbines are used to propel various vehicles,airplanes, ships, etc. In the oil and gas field, the gas turbines areused to drive compressors, pumps and/or generators. As shown in FIG. 1,a gas turbine 12 may be connected to a compressor or generator 14 and toan auxiliary equipment 16. A gear box 18 or other equipment may beprovided between the gas turbine 12 and the compressor or generator 14.All these elements form a turbo-compressor train 10.

The gas turbine 12 may include a compressor 20 that is configured toreceive a gas (e.g., air) at an input 22 and to provide the gascompressed to a predetermined pressure at an outlet 24. The compressedgas is then input to a combustor 26 where it is mixed with a fuelprovided from a line 28. The mixture of gas and fuel is ignited and thehot gases at high pressure are provided to an input 30 of an expander32. The exhaust gases are then released at output 34 of the expander 32.

The expansion of the hot gases through the expander 32 determines arotation of a rotoric part (not shown) which is coupled, through thegear box 18 to a shaft of the compressor 14. Thus, the compressor 14 isdriven by the expander 32. One or more of the components of theturbo-compressor train 10 involves heavy rotoric parts (e.g., shaft,impeller, etc.) that rotate at a high speed. In order to promote therotational motion of these components and to minimize the friction,various bearing units are provided in the train. A few arrangements arediscussed next.

FIGS. 2A-C show the train 10 of FIG. 1 in which some elements haverolling bearings and the remaining elements have hydro-dynamic bearings.Those elements having the rolling bearings are identified with A andthose having the hydro-dynamic bearings are identified with B. Further,it is noted that the rolling bearings need to use synthetic oil whilethe hydro-dynamic bearings need to use mineral oil. Thus, thearrangements shown in FIGS. 2A and 2B need two lube pumps, one for eachtype of bearings while the arrangement shown in FIG. 2C uses one lubepump and the mineral oil. These arrangements have a higher weight andmaintenance cost due to the dual lube pump, they have a large footprintand require higher plant complexity. A disadvantage of the configurationshown in FIG. 2C is the higher lube oil consumption needed forhydrodynamic bearings.

Accordingly, it would be desirable to provide systems and methods thatavoid the afore-described problems and drawbacks.

BRIEF SUMMARY OF THE INVENTION

According to one exemplary embodiment, there is a turbo-compressor trainthat includes a gas turbine configured to transform thermal energy intomechanical energy; a centrifugal compressor having a shaft connected toa shaft of the gas turbine; and a single lube pump configured to providesynthetic oil to the gas turbine, and the centrifugal compressor. Thegas turbine, the centrifugal compressor and the single lube pump eachhas only rolling bearings.

According to another exemplary embodiment, there is a turbo-compressortrain that includes a gas turbine configured to transform thermal energyinto mechanical energy; a generator having a shaft connected to a shaftof the gas turbine; and a single lube pump configured to providesynthetic oil to the gas turbine, and the generator. The gas turbine,the generator and the single lube pump each has only rolling bearings.

According to still another exemplary embodiment, there is a method forassembling a turbo-compressor train. The method includes mechanicallyconnecting a gas turbine to a centrifugal compressor; mechanically orelectrically connecting a lube pump to the gas turbine; and providingeach of the gas turbine, the centrifugal compressor and the lube pumponly with rolling bearings and the lube pump is configured to pumpsynthetic oil.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate one or more embodiments and,together with the description, explain these embodiments. In thedrawings:

FIG. 1 is a schematic diagram of a conventional turbo-compressor train;

FIGS. 2A, 2B, and 2C are schematic diagrams of conventionalturbo-compressor trains having two lube pumps or being supplied onlywith mineral oil;

FIG. 3 is a schematic diagram of a rolling bearing according to anembodiment of the present invention;

FIG. 4 is a schematic diagram of a hydro-dynamic bearing according to anembodiment of the present invention;

FIG. 5 is a schematic diagram of a turbo-compressor train having asingle lube pump according to an exemplary embodiment;

FIG. 6 is a schematic diagram of a turbo-compressor train having asingle lube pump electrically connected to the train according to anexemplary embodiment;

FIG. 7 is a schematic diagram of a centrifugal compressor according toan exemplary embodiment;

FIG. 8 is a schematic diagram of another turbo-compressor train having asingle lube pump according to an exemplary embodiment; and

FIG. 9 is a flowchart of a method for assembling a turbo-compressortrain with a single lube pump according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE INVENTION

The following description of the exemplary embodiments refers to theaccompanying drawings. The same reference numbers in different drawingsidentify the same or similar elements. The following detaileddescription does not limit the invention. Instead, the scope of theinvention is defined by the appended claims. The following embodimentsare discussed, for simplicity, with regard to the terminology andstructure of a gas turbine system connected to a compressor orgenerator. However, the embodiments to be discussed next are not limitedto these systems, but may be applied to other systems that have pluralmachines connected to each other and each machine has its own bearingsystem.

Reference throughout the specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with an embodiment is included inat least one embodiment of the subject matter disclosed. Thus, theappearance of the phrases “in one embodiment” or “in an embodiment” invarious places throughout the specification is not necessarily referringto the same embodiment. Further, the particular features, structures orcharacteristics may be combined in any suitable manner in one or moreembodiments.

According to an exemplary embodiment, the components of an entireturbo-compressor train are provided with rolling bearings. Thus, nocomponent has hydro-dynamic bearings, which is different from thetraditional trains in which the compressors have hydro-dynamic bearings.In this regard, it is noted that traditional centrifugal compressors donot have rolling bearings because for this solution it is more complexto compensate the axial thrust. Moreover, the dynamic behavior of thecompressor with rolling bearings is negatively influenced by the highstiffness, while the solution with hydrodynamic bearings is much moredamped. In this exemplary embodiment, a single lube pump is used for allthe components, which results in a lower weight of the train, lowermachine cost, lower footprint, and higher reliability. By removing themineral lube oil pump for the hydro-dynamic bearings, depending on themachine, up to 250 kW of energy may be saved. Therefore, according tothis exemplary embodiment, all the components of the train use syntheticoil. The single lump pump may be part of the train or may be anauxiliary component of the train. The lump pump may be mechanically orelectrically connected to the train.

Prior to discussing the arrangement of the novel train, a briefdescription of a rolling bearing, hydro-dynamic bearing, mineral oil andsynthetic oil is believed to be in order. A generic rolling bearing 50is shown in FIG. 3. The rolling bearing 50 includes two races, anexterior race 52 and an interior race 54. These two races guide rollingelements 56. The rolling elements 56 may be balls, as shown in thefigure, or may have other shapes, e.g., cylinders, etc. They may betapered or not. A cage 58 may be used for keeping the rolling elementsat desired distances one from the other. Other types of rolling bearingsexist and are known in the art.

The rolling bearing 50 shown in FIG. 3 is traditionally lubed withsynthetic oil or grease, depending on the application. Synthetic oil isa lubricant that includes chemical compounds which are artificially made(synthesized). The synthetic lubricants can be manufactured usingchemically modified petroleum components rather than crude oil, but canalso be synthesized from other raw materials. Synthetic oil is used as asubstitute for lubricant refined from petroleum when operating inextreme temperature, because it generally provides superior mechanicaland chemical properties than those found in traditional mineral oils.

A generic hydro-dynamic bearing 60 includes a ring 62 that is configuredto hold plural pads 64, each having a working surface 64 a. The pads 64are retained by a blocking plate 66 to prevent them from sliding in arotational direction A when a shaft (not shown) rotates at high speedsinside the ring 62, in direction A. Corresponding retention plates 68,for preventing axial dislocation, retain the pads 64 in the proximity ofthe ring 62. Ring 62, blocking plate 66 and retention plates 68 define apredetermined volume in which pad 64 may pivot about a retaining head(not shown). Mineral oil is provided on the working surface 64 a so thatan oil film forms between the rotating shaft (not shown) and the pads64.

The mineral oil is a liquid by-product of the distillation of petroleumto produce gasoline and other petroleum based products from crude oil.The mineral oil includes mainly alkanes (typically 15 to 40 carbons) andcyclic paraffins, related to petroleum jelly (also known as “whitepetrolatum”).

As discussed above, according to an exemplary embodiment, aturbo-compressor train is configured to have only rolling bearings andno hydro-dynamic bearings. Thus, when the compressor in theturbo-compressor train is a centrifugal compressor, no hydro-dynamicbearings are used. In this regard, it is noted that the conventionalcentrifugal compressors do not use rolling bearings but onlyhydro-dynamic bearings.

FIG. 5 shows an exemplary embodiment of a turbo-compressor train 100having all components provided with rolling bearings and nohydro-dynamic bearings. The turbo-compressor train 100 includes acompressor 102 fluidly connected to a combustion chamber 104 in whichfuel and air are mixed together and ignited. The hot gases are providedto an expander 106 whose shaft is rotated by the expansion of the hotgases. The expander 106 may be an axial expander. A shaft 108 of theexpander 106 may be connected to a shaft 110 of a centrifugal compressor112 and also to the compressor 102. A shaft of the compressor 102 may beconnected to an auxiliary gear box 114 that is configured to transmitrotational motion to a shaft of a pump 116. The pump 116 may be the lubepump for the synthetic oil necessary to the rolling bearings of thevarious components of the turbo-compressor train.

According to an exemplary embodiment illustrated in FIG. 6, a train 200includes all the components shown in FIG. 5 for the train 100 exceptthat the pump 216 is not part of the train. Further, the pump 216 is notmechanically (rotational motion) connected to the train. In thisexemplary embodiment, the pump is supplied with, for example, electricalpower from a power source 218 (e.g., power grid or a power generator ofthe train). In this regard, it is noted that all the embodimentsdiscussed in this application (e.g., FIGS. 5 and 8) may have the pumpeither mechanically or electrically connected to the train. Further, thepump may or may not be part of the train, depending on the application.

According with an exemplary embodiment, the pump 116, the auxiliarygearbox 114, the compressor 102, the expander 106, and the centrifugalcompressor 112 each has rolling bearings. Thus, according to thisexemplary embodiment, a single lube pump is used and the only oil usedis the synthetic oil. In one application, the centrifugal compressor 112may be replaced by a generator. In this case, the generator has rollingbearings and not hydro-dynamic bearings. Because the rolling bearingsmay not support enough axial trust in comparison to the hydro-dynamicbearings, a dedicated thrust balance system (developed by the assigneeof this patent application) may be necessary.

A generic centrifugal compressor 140 modified as discussed above isshown in FIG. 7 and is defined by the fact that air intake reaches alongan X direction, at position 142, an impeller 144 and exits along a Ydirection at position 146 having increased the speed of the air due tothe centrifugal motion through the impeller 144. The impeller 144 isshown connected to the shaft 110, which is supported by the rollingbearings 148 and 150.

Returning to FIG. 5, it is noted that piping 170 connects the lube pump116 to each of the components of the turbo-compressor train forsupplying the necessary synthetic oil. According to an exemplaryembodiment illustrated in FIG. 8, a gearbox 180 may be provided betweenthe shaft 108 of the expander 106 and the shaft 110 of the centrifugalcompressor or generator 112. In this case, the gearbox 180 is configuredto use synthetic oil and, if necessary, rolling bearings.

According to an exemplary embodiment illustrated in FIG. 9, a method forassembling a train as discussed above is described. The method includesa step 900 of mechanically connecting a gas turbine to a centrifugalcompressor; a step 902 of mechanically or electrically connecting a lubepump to the gas turbine; and a step 904 of providing each of the gasturbine, the centrifugal compressor and the lube pump only with rollingbearings and the lube pump is configured to pump synthetic oil.

The disclosed exemplary embodiments provide a turbo-compressor and amethod for providing rolling bearings to each component of theturbo-compressor. It should be understood that this description is notintended to limit the invention. On the contrary, the exemplaryembodiments are intended to cover alternatives, modifications andequivalents, which are included in the spirit and scope of the inventionas defined by the appended claims. Further, in the detailed descriptionof the exemplary embodiments, numerous specific details are set forth inorder to provide a comprehensive understanding of the claimed invention.However, one skilled in the art would understand that variousembodiments may be practiced without such specific details.

Although the features and elements of the present exemplary embodimentsare described in the embodiments in particular combinations, eachfeature or element can be used alone without the other features andelements of the embodiments or in various combinations with or withoutother features and elements disclosed herein.

This written description uses examples of the subject matter disclosedto enable any person skilled in the art to practice the same, includingmaking and using any devices or systems and performing any incorporatedmethods. The patentable scope of the subject matter is defined by theclaims, and may include other examples that occur to those skilled inthe art. Such other examples are intended to be within the scope of theclaims.

What is claimed is:
 1. A turbo-compressor train, the train comprising: agas turbine configured to transform thermal energy into mechanicalenergy; a centrifugal compressor comprising a shaft connected to a shaftof the gas turbine; and a single lube pump configured to providesynthetic oil to the gas turbine, and the centrifugal compressor,wherein the gas turbine, the centrifugal compressor and the single lubepump each has only rolling bearings.
 2. The turbo-compressor train ofclaim 1, wherein the gas turbine comprises: a compressor configured tocompress air; a combustion chamber configured to receive the compressedair from the compressor and to ignite the compressed air after mixing itwith fuel; and an expander configured to receive hot gases from thecombustion chamber and to transform the thermal energy of the hot gasesinto rotational motion.
 3. The turbo-compressor train of claim 1,further comprising: an auxiliary gearbox connecting a shaft of the gasturbine to a shaft of the lube pump and the auxiliary gearbox isconfigured to work with synthetic oil, or a power source configured toprovide energy to activate the lube pump.
 4. The turbo-compressor trainof claim 1, further comprising: piping connecting the lube pump to thegas turbine and the centrifugal compressor for distributing thesynthetic oil.
 5. The train turbo-compressor of claim 1, wherein nomineral oil is used in any component of the train.
 6. Theturbo-compressor train of claim 1, wherein the gas turbine comprises anaxial expander.
 7. The turbo-compressor train of claim 1, furthercomprising: a gearbox configured to mechanically connect a shaft of thegas turbine and a shaft of the centrifugal compressor.
 8. Theturbo-compressor train of claim 1, further comprising: an auxiliarygearbox connecting a shaft of the gas turbine to a shaft of the lubepump and the auxiliary gearbox is configured to work with synthetic oil;piping connecting the lube pump to the gas turbine and the centrifugalcompressor for distributing the synthetic oil; and a gearbox configuredto mechanically connect a shaft of the gas turbine and a shaft of thecentrifugal compressor, wherein the gas turbine further comprises: acompressor configured to compress air; a combustion chamber configuredto receive the compressed air from the compressor, to mix the compressedair with fuel, and to ignite the compressed air mixed with fuel; and anexpander configured to receive hot gases from the combustion chamber andto transform the thermal energy of the hot gases into rotational motion.9. A turbo-compressor train, the train comprising: a gas turbineconfigured to transform thermal energy into mechanical energy; agenerator comprising a shaft connected to a shaft of the gas turbine;and a single lube pump configured to provide synthetic oil to the gasturbine, and the generator, wherein the gas turbine, the generator andthe single lube pump each has only rolling bearings.
 10. A method forassembling a turbo-compressor train, the method comprising: mechanicallyconnecting a gas turbine to a centrifugal compressor; mechanically orelectrically connecting a lube pump to the gas turbine, wherein the lubepump is configured to pump synthetic oil; and providing each of the gasturbine, the centrifugal compressor, and the lube pump only with rollingbearings.
 11. The turbo-compressor train of claim 9, wherein the gasturbine comprises: a compressor configured to compress air; a combustionchamber configured to receive the compressed air from the compressor andto ignite the compressed air after mixing it with fuel; and an expanderconfigured to receive hot gases from the combustion chamber and totransform the thermal energy of the hot gases into rotational motion.12. The turbo-compressor train of claim 9, further comprising: anauxiliary gearbox connecting a shaft of the gas turbine to a shaft ofthe lube pump and the auxiliary gearbox is configured to work withsynthetic oil, or a power source configured to provide energy toactivate the lube pump.
 13. The turbo-compressor train of claim 9,further comprising: piping connecting the lube pump to the gas turbineand the generator for distributing the synthetic oil.
 14. The trainturbo-compressor of claim 9, wherein no mineral oil is used in anycomponent of the train.
 15. The turbo-compressor train of claim 9,wherein the gas turbine comprises an axial expander.
 16. Theturbo-compressor train of claim 9, further comprising: a gearboxconfigured to mechanically connect a shaft of the gas turbine and ashaft of the generator.
 17. The turbo-compressor train of claim 9,further comprising: an auxiliary gearbox connecting a shaft of the gasturbine to a shaft of the lube pump and the auxiliary gearbox isconfigured to work with synthetic oil; piping connecting the lube pumpto the gas turbine and the generator for distributing the synthetic oil;and a gearbox configured to mechanically connect a shaft of the gasturbine and a shaft of the generator, wherein the gas turbine furthercomprises: a compressor configured to compress air; a combustion chamberconfigured to receive the compressed air from the compressor, to mix thecompressed air with fuel, and to ignite the compressed air mixed withfuel; and an expander configured to receive hot gases from thecombustion chamber and to transform the thermal energy of the hot gasesinto rotational motion.